The present invention relates generally to a fuel burner pumping system having means for purging air from the system. More particularly, the invention relates to a system in which such means includes an air purging valve located within an outlet passage leading from a fuel pump to a nozzle passage so as to by-pass a fuel pressure control valve so that air from the system is exhausted directly into the nozzle passage.
In one prior system of the foregoing type, fuel from a supply is drawn through a line by a crescent gear pump and is fed under pressure into the main chamber of a pressure control valve through an outlet passage communicating between the pump and the chamber. From the main chamber, the pressurized fuel flows through an outlet port into a passage communicating with a burner nozzle or nozzles. An air purging valve is disposed within a second outlet passage by-passing the main chamber outlet port so as to communicate directly with the nozzle passage. In this prior system, the air purging valve is spring-biased toward a closed position to shut off fuel flow through the second outlet passage when the pump is inoperative and the fuel pressure within the system is lower than the air pressure capable of being generated by the pump. To purge air from the system as the pump is started, the valve opens after the fluid pressure in the system becomes sufficient to overcome the biasing force of the spring. The purging valve remains open as long as the fluid pressure within the system is sufficient to overcome the spring. Accordingly, during normal operation of the pump, fluid flows into the nozzle passage through both the outlet port of the main chamber and the second outlet passage.
Oil burner pumping sytems of the foregoing broad general character are disclosed in U.S. Pat. Nos. 3,566,901; 3,446,232; 3,446,231; and 3,446,230. Other systems having air purging means are disclosed in U.S. Pat. Nos. 3,273,513; 3,143,967; 2,931,314; 2,915,015; and 2,763,336.